Drawing sheet glass



June 3, 1930.

c. A. ROWLEY DRAWING SHEET GLASS Original Filed July 24. 1922 2 Sheets-Sheet l 'ii -3; 1930. c. A. RowLEY 1,761,234

DRAWING SHEET GLASS original Filed July 24, 1922 2 Sheets-Sheet 2 [IVY/ENTER l atented June 3, 1930 UNITED STATES PATENT OFFICE CLIFFORD A. ROWLEY, OF TOLEDO, OHIO, ASSIGNOR TO LIBBEY-OWENS GLASS COMPANY,

' F TOLEDO, OHIO, .A. CORPORATION" OF OHIO DRAWING SHEET GLASS Application filed July 24, 1922, Serial No. 578,922. Renewed July 7, 1924.

This invention relates tothe art of drawing continuous sheet glass, and more par-' ticularly to a new method and apparatus for imparting a lateral tension or sidewise stretch to the sheet, at and adjacent its source.

The principles of this invention are applicable to any system of drawing sheet glass, but are here illustrated in connection with the Colburn sheet drawing system, as set forth,

for example, in the patent toI. W. Colburn,

1,248,809, granted Dec. at, 1917. In this system a sheet of glass is drawn upwardly from a bath of molten glass, bent laterally, while still somewhat plastic, over a cooled bending roller, and then drawn off horizontally through a suitable flattening mechanismand into a leer. A pair of driven edge-gripping rollers, rotating at a slower peripheral speed than the main sheet drawing means, engage each edge of the sheet at its source. The rollers are internally cooled for the double purpose of protecting the rollers from the heat, and for cooling the edges of the sheet. These rollers positively feed up the molten glass into the sheet edges, and at the same time form cool stiff edges on the sheet and hold back on the edges, putting an added longitudinal tension thereon. The function and effect of these rollers is to keep the sheet to width and prevent the gradually narrowing away that would take place if the edge rollers were not used. Y

It has often been conceived that it would be desirable to impart alateral or sidewise tension to the sheet during its forming period, to eliminate, or prevent the formation of waves, wrinkles or corrugations that are sometimes present in drawn sheet glass. All such prior mechanisms for this purpose, as have been designed for use with a machine of the Colburn type, could not engage the sheet sufficiently near its source due to the presence at that point of the edge-forming rollers already described. And it is in this initial forming zone, where the sheet is still quite soft and plastic, that it is most susceptible to a lateral stretching action. If the formation of waves or wrinkles is to be forestalled or prevented, it is essential that the 50 side stretching or lateral tension shall be apglass, about to the upper limit of this initial plied at the very source of the sheet and continued through this critical forming period. This initial forming zone for thesheet is only a few inches long, varying somewhat with the temperature conditions, the thickness of the sheet, and the speed of draw.

In the system here disclosed, the edgeforming rollers have been retained but have been elevated somewhat above the molten forming zone. The side-stretching means are placed below the edge-forming rollers, and between these rollers and the pool of molten glass. The edge rollers function much the same as before, with the additional function of positively drawing the sheet edges up through the side-stretching devices.

The objects and advantages of the invention will become more apparent from the following detailed description of one approved form of apparatus for carrying out the principles of the invention.

In the accompanying drawings:

Fig. 1 is a longitudinal vertical section through a portion of the sheet drawing apparatus.

Fig. 2 is a partial transverse vertical sectii on, taken substantially on the line 22 of Fig. 3 is a plan view of one set of the edge forming and stretching devices, the view betaken substantially on the line 33 of Fig. 4 is an enlarged section through one of the side stretching cones.

Fig. 5 is a longitudinal section through one of the knurled edge-gripping rollers.

At 1 is shown the discharge end of a continuous tank furnace, or other source of molten glass, from which the molten glass 2 flows into the receptacle or draw-potS from which the sheet 4 is drawn. A considerable area of the molten glass in receptacle 3 is covered by the lip-tiles 5, and this glass is maintained at the proper temperature by the heating chamber 6 below the receptacle and by burners 7 beneath the'lip-tiles 5. The exposed molten glass betweenthe lip-tiles 5 is cooled and rendered more tenacious by the coolers 8, through which. a circulation of 100 water is maintained, and the sheet is drawn up between the coolers from this tenacious semi-plastic glass. The sheet 4 is drawn over a cooled bending roller 9, and intermediate supporting rollers 10 and 11, into the drawing and flattening mechanism 12, from which it passes into the annealing leer (not shown). All of the above is typical of the Colburn sheet drawing apparatus, disclosed in the patent already referred to, and need not be further described.

Each edge of the sheet 4, throughout substantially the entire initial forming zone Z (see Fig. 2), is drawn up between a pair of members rotatable at right-angles to the line of travel of the sheet, here shown as inverted cones 13. These cones are supported and freely rotatable on suitable hearings on the downturned ends 14 of the stationary tubular rods 15. The lower rounded ends 16 of these cones engage the sheet edges at their source, practically in the same places now engaged by the edge-forming rollers in the Colburn apparatus already referred to. The cones are slowly rotated inthe direction of the arrows, Fig. 3, by mechanism which will be later described. The outer surfaces of the cones are preferably fluted, as indicated at 17, to insure a better grip on the sheet edge. 0116 of the supporting rods 15 is rigidly mounted in a fixed bracket 18 projecting up from a stationary supporting base 19. The-other rod 15 is rigidly mounted in a supporting bracket 20, pivotally mounted on vertical pivot 21 in the supporting base 19.

A circulation of water or other cooling fluid is maintained through each of the cones, to prevent the destruction of the cone in the intense heat, and also to exert a cooling effect on the sheet edge. The water flows in at 22, passing through the interior pipe 23 to the lower end 16 of the cone. It then flows up through the cone, as indicated by the arrows, Fig. 4, and enters the .downturned end 14 of rod 15 through the openings 24. Thence it flows out through supporting rod 15, and out-flow pipe 25.

Mounted immediately above each pair of edge-gripping cones are a pair of edge-gripping rollers 26, which draw the sheet edge longitudinally, that is their drawing action is at right-angles to the drawing action'of cones 13. These rollers 26are much the same, both in form and function, as the-edge forming rollers already described-in connection with the patented Golburn mechanism.

These rollers 26have-aknurled or roughened surfaceto insure agood grip on the glass sheet, andare carried at the inwardly projecting ends of rotatingshafts 27. 'One of these shafts 27 is journaled at a point intermediateits endszin bearing28, carried by the adjacent supporting rod 15, and its outer end is :journaled in bearing 29, formed as a partof the stationary bracket 18. The other shaft 27 is mounted in the intermediate bearing 30, projecting from the adjacent supporting rod 15, and its outer end is journaled in bearing 31, formed as a part of the pivotally supported bracket 20, already described. A circulation of water or other cooling fluid is maintained through each of the rollers 26, the water flowing in through pipe 32 and out through the shaft 27, and the out-flow pipe 33.

An expansion spring 34 is confined between a portion of the fixed bracket 18 and an adjusting screw carried by the pivoted bracket 20. This sp ring yieldably clamps the sheet edge between the cones 13 and rollers 26 at the two sides of the sheet edge. \Vhcn the machine is started, or at anytime when it is desired to remove this edge gripping mechanism, the unit at one side of the sheet edge, consisting of one cone l3 and roller 26 and their supports, may be swung away from the sheet by compressing the spring 34. The pressure of the parts on the sheet edge may be adjusted at any time by means of screw 35.

The shaft 27 that is mounted in the fixed bracket 18, is rotated through bevel-gears 3G and 37 from (hive-shaft 38. The other shaft 2." is driven from its companion shaft 27 through intermeshing spur gears 39 and 40 keyed to the respective shafts. Thus the rollers '26 are driven in opposite directions and act to feed the sheet edge up between them. A spur gear 41 keyed to each shaft 27, meshes with and drives a spur gear 42 at one end of sleeve 43 rotatable on the supporting rod 15. A bevel. gear 44 at the other end of this sleeve, meshes with and drives a bevel gear secured to the upper face of the cone 13. Th cones 13 will thus be slowly rotated so that the sheet edge gripped therebetween will be drawn outwardly, imparting a lateral stretch or tension to the, sheet. Each sleeve 43 is confined between the adjacent bearing 28 and a collar -16 formed on the rod 15. I

In the example here illustrated, the bevelgear 45 also serves as a closure for the upper end of the hollow cone. A suitable packing or hearing at 47 will prevent the leakage of the cooling fluid from the interior of the cone.

In operation, the sheet as an entirety is drawn up from pool 2 and over the roller 9 by drawing mechanism 12, the drawing force being applied to the set sheet which acts as a bait to draw more sheet from the molten source. At the same time the edge-portions of the sheet are drawn up from the pool, be tween the engaging surfaces of the cones 13. by the edge-gripping rollers 26. The sheet edges will slide up along the fluted surfaces ofthe cones. The lower ends of the cones rotate very slowly, inst fast enough to prevent the molten glass from adherin; thereto. '..he periphery of the cone has a gradually increasing speed as the larger upper end is approached, and the sheet edge which has been pulled into engagement with the fluted surfaces at the lower end of the cone is gradually drawn outwardly while sliding up along the cone. Only a small amount of stretch is nec essary, so the cones rotate slowly, but their peripheral speed at the top is somewhat greater than the required stretch, as there will be a certain amount of slippage between the conical surfaces and the edge portion of the glass sheet.

The edge drawing rollers 26 have a somewhat slower peripheral speed than the drawing speed of the sheet as imparted by the mechanism 12. This gives a stretching tension between the rollers 26 and bending roll 9 (as in the present Colburn machine), as well as the longitudinal stretch between the sheet source and rollers .26, caused by dragging the sheet between the surfaces of the cones.

It will be noted that with this apparatus,

the normal drawing operation, whereby the entire sheet is under longitudinal stretching tension from its source until set, and the edge portions are subjected to an additional longitudinal tension to prevent narrowing of the sheet, is not interfered with. At the same time the sheet is subjected to a'lateral orsidewise stretching tension from its very source up through that initial forming zone wherein it is most plastic and susceptible to such stretching action. The sheet, during this entire formative period is under both longitudinal and lateral tension, and the formation of waves and wrinkles due to lack of side-tension is precluded Claims:

1'. The method of producing sheet glass,

consisting in drawing the sheet from a supply of molten glass, the drawing force being applied to the set sheet at some distance from the molten source, drawing the sheet edges from the source at points adjacent the source at a slower speed than the rate of draw of the sheet, and simultaneously but independently applying lateral or sidewise tension to the sheet edges between the source and the points of application of the edge drawing force.

2. in an apparatus for stretch ng a drawn sheet of glass laterally while it is talnng form nearits source, pair of inverted cones between which the sheet edge is gripped, the sheet engaging surfaces of the cones moving outwardly at right-angles to the direction of travel of the sheet.

3. In an apparatus for stretching a drawn sheet of glass laterally while it is taking form near its source, a pair of inverted cones having fluted sheet engaging surfaces between which the sheet edge is gripped, the sheet engaging surfaces of the cones moving outwardly at right-angles to the direction of travel of the sheet.

4. In a sheet glass drawing mechanism, a

receptacle.containing a pool of molten glass, means for drawing a sheet of glass therefrom, and two superposed sets of supplemental drawing means acting at right angles to each other 6n the sheet edges near their source, the lower sets stretching the sheet laterally and the upper sets drawing it longitudinally.

5. In a sheet glass drawing mechanism, a receptacle containing a pool of molten glass, means for drawing a sheet of glass therefrom, means grasping the sheet edges through the initial forming zone and stretching the sheet dewise or laterally, and supplemental edge-drawing means located just beyondthis zone for drawing the sheet edges longitudinally through the stretching zone, these supplemental edge-drawing means having a slower drawing speed than the main sheetdrawing means, whereby they exert a retarding influence on the sheet edges which have passed beyond the supplemental means.

(3. In a sheet glass drawing mechanism, a source of molten glass, means for continuously drawing a sheet glass therefrom, means for stretching the sheet laterally at its source comprising pairs of rotating members between which the sheet edge is gripped, the sheet engaging surfaces of the members moving outwardly at right-angles to the direction of draw of the sheet, and supplemental edge-drawing means for drawing the glass from the source between the rotating members at ri ht-angles to the direction of movement of their surfaces.

7. In a sheet glass drawing mechanism, a source .ofmolten glass, means for continuously drawing a sheet of glass therefrom, means for stretching the sheet laterally at its source con'iprising pairs of rotating inverted cones between which the sheet edge is gripped, the sheet engaging surfacesof the cones moving outwardly at right-angles to the direction of draw of the sheet, and snppleim-uital edge-draw1ng means for drawing the glass from the source between the rotating cones at right angles to the direction of movement of their surfaces.

8. In a sheet glass drawing mechanism, a source of molten glass, means for continuously drawing a sheet of glass therefrom, means for stretching the sheet laterally at its source comprising pairs of rotating members between which the sheet edge is gripped, the sheet engaging surfaces of the members moving outwardly at right-angles to the direction of draw of the sheet, and supplemental edge-drawing members rotating at right angles to the first members, for drawing the sheet edges longitudinally from the molten source between the first members.

9. In a sheet glass drawing mechanism, a

means for stretching the sheet laterally at its source comprising pairs of rotating inverted cones between which the sheet edge is gripped, the sheet engaging surfaces of the cones moving outwardly at right-angles to the direction of draw of the sheet, and edgedrawing rollers rotating at right-angles to the cones, for drawing the sheet edge longitudinally from the molten source between the cones.

10. In a sheet glass drawing apparatus, the combination with means for drawing the sheet from its moi ten source, of means for applying lateral tension to the sheet in that zone adjacent source wherein it is taking form, conu rising members which rotate at right angles to the line or travel of the sheet, and grip the sheet edges to pull them laterally, and edge-gripping rollers positioned immediately eyond these members for drawing the sheet edges :lrom the source and between the rotating members.

11. In a sheet glass drawing apparatus, the combination with means for drawing the sheet from molten source, of means for applying lateral tension to the sheet in that zone adjacent its source wherein it is taking form, comprising at each edge of the sheet a pair of inverted cones between which the sheet edge is yieldably gripped, means for rotating the cones at right-angles to the direction of travel of the s ieet, means for internally cooling the cones, a pair of rollers engaging the sheet edge immediately beyond the cones, means for cooling the rollers, and means for rotating the rollers in the direct-ion of travel or the sheet, the Cones functioning to stretch the sheet sidewise, and the rollers drawing the sheet edges longitudinally between the cones.

12. The method of producing sheet glass,

consisting in drawing the sheet from a supply of molten glass, the drawing means being applied to the sheet at some distance from the molten source, holding the sheet edges adjacent the source against lateral contraction, and applying additional drawing force to the sheet edges immediately above the edge holding means.

13. In a sheet glass drawing mechanism, a receptacle containing a pool of molten glass, means for drawing a sheet oi glass therefrom, means engaging the sheet edges through the initial forming Zone and holding the sheet against lateral contraction, and supplemental edge drawing means positioned just beyond the edge holding means for sliding the sheet edges longitudinally through the holding means.

14. In the method of making sheet glass, the steps consisting in drawing a sheet of glass upwardly from a molten bath and then carrying it over a bending roll, engaging the edges of the sheet below the bending roll and drawing the edge portions of the sheet upwardly, and slidably engaging the edge portions of the sheet between the bath and the first mentioned point oi. engagement of the edge portions to resist the upward movement of the glass and stretch the sheet, substantially as described.

15. Sheet glass drawing apparatus, including a molten bath, knurled rolls for engaging the edge portions of a glass sheet and assisting in drawing it upwardly therefrom, rolls between the knurledrolls and the bath for resisting the upward movement of the sheet and stretch the same, means for driving the rolls in an opposing direction to the direction of the travel of the glass, and means for adj-ustingthe position of the rolls, substantially as described.

16. Sheet glass drawing apparatus, including a molten bath, knurled rolls for engaging the edge portions of a glass sheet and assist ing in drawing it upwardly from the bath, rolls between the knurled rolls and the bath for frictionally engaging the sheet to resist its upward movement and stretch the same, means for driving the rolls in an opposed direction to the direction of travel of the glass, and means for adjusting the position of the rolls and the knurled rolls, substantially as described.

17. Sheet.v glass drawing apparatus includin g a molten bath, a bending roll, a plurality of :nurled rolls arranged in pairs located between the bending roll and the molten bath, the rolls of each pair engaging opposite sides of the edge portions of the sheet and assisting in drawing it upwardly from the molten bath, means for positively rotating said rolls, a second set of rolls likewise arranged in pairs located between said first named rolls and the molten bath and engaging the edge portions of the sheet, means for positively driving said last named rolls in a direction other than the direction of rotation of the first named rolls to resist the upward movement of the sheet, bearing blocks for the driving means of the last named rolls, means, including a yielding connection beneath the bearing blocks, tending to force at least one of said last named rolls toward the other and into contact with the edge portions of the sheet, and means for regulating the pressure of the yielding connection.

Signed at Toledo, in the county of Lucas, and State oi Ohio, this 21st day of July, 1922.

CLIFFORD A. ROWVLEY. 

